Low voltage power line communication for climate control system

ABSTRACT

A system for controlling one or more components of a climate control system is provided that includes one or more controllers in connection with low voltage power lines for powering the one or more controllers. The controllers are further capable of transmitting one or more communication signals via the low voltage waveform. The system includes a thermostat controller, at least one system controller for a heating or cooling system, and a controller for a circulating air blower. The thermostat controller, system controller and circulating air blower controller are connected to each other only through each controller&#39;s individual connection to the hot and common low voltage power transmission lines. Each controller is capable of transmitting one or more signals that are superimposed onto the low-frequency low-voltage waveform and include information identifying a destination controller that the signals are intended for.

FIELD OF THE INVENTION

The present invention relates to controllers for interactivelycontrolling an HVAC system, and more particularly to an integratedsystem of HVAC controls for interactively controlling various componentsin the HVAC system

BACKGROUND OF THE INVENTION

In present residential heating, ventilating and air conditioningsystems, a 24 volt alternating current (AC) transformer provides lowvoltage power source for actuation of various components of the HVACsystem. A wall thermostat within the space typically receives 24 voltAC, and transmits a 24 volt AC signal via a wire to a heating controllerto request or activate heating, or via a second wire to an airconditioning compressor contactor to request or activate cooling. A 24volt AC signal for requesting heating may be used to directly turn on a24 volt AC electromechanical device to actuate heating, or the signalmay be interpreted by the heating controller as an “on” signal. The 24volt AC signal may be interpreted as “on” or “off” depending on thepresence or absence of the 24 volt AC signal. For each additionalthermostat command for other system components, such as a fan, heatpump, humidifier, etc., typically at least one new wire is required forthe thermostat to transmit a 24 volt AC signal to the additionalcomponent. In the new construction of a building, the amount of wiringinstalled from the thermostat through the walls to the HVAC systemcomponents will accordingly depend on the complexity of the particularHVAC system. An HVAC system typically requires wiring for componentssuch as a furnace controller, an air conditioning compressor relay orcontactor, and a fan, but may require additional wiring for a heat pumpor staged heating, staged cooling, a humidifier, an air cleaner, orother components. Once the construction is completed and the wiring isin place, subsequent replacement of the HVAC system can be affected bythe number of existing wires installed from the thermostat through thewalls. Likewise, replacing an older HVAC system and thermostat connectedto each other by a minimum number of wires with a newer HVAC systemhaving more functions may require the installation of more wiring, whichcan be labor intensive and costly.

SUMMARY OF THE INVENTION

Various embodiments of a system for controlling one or more componentsof a climate control system are provided that include one or morecontrollers in connection with low voltage power lines for powering theone or more controllers. The controllers are further capable oftransmitting one or more communication signals via the low voltagewaveform. In one embodiment of a system for controlling at least onecomponent of a climate control system comprises an alternating currentpower source that conducts a low-frequency low-voltage waveform acrosshot and common power transmission lines. The system includes athermostat controller, a system controller for a heating or coolingsystem, and a controller for a circulating air blower. The thermostatcontroller, system controller and circulating air blower controller areconnected to each other only through each controller's individualconnection to the hot and common low voltage power transmission lines.Each controller is capable of transmitting one or more signals that aresuperimposed onto the low-frequency low-voltage waveform and includeinformation identifying a destination controller that the signals areintended for.

In another embodiment of the present invention, a system is provided forcontrolling a climate control system that comprises an alternatingcurrent power source that conducts a low-frequency low-voltage waveformacross hot and common power transmission lines. The system furthercomprises a thermostat controller, a controller for a heating system,and at least a controller for a compressor of a heat pump or airconditioning system. The thermostat controller, heating systemcontroller and compressor controller are connected to each other onlythrough each controller's individual connection to the hot and commonpower transmission lines. Each controller is capable of transmitting oneor more signals that are superimposed onto the low-frequency low-voltagewaveform and include information identifying a destination controllerthat the signals are intended for. At least one controller is capable ofmodifying the operation of at least one component that the at least onecontroller has control over in response to receiving a signal that isintended for another controller which includes information about theoperation of at least one component within the climate control system.

In another aspect of the present invention, some embodiments furtherinclude at least one controller that is capable of modifying theoperation of at least one component that the at least one controller hascontrol over, in response to receiving a signal that is intended foranother controller which includes information about the operation of acomponent within the climate control system.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is an illustration of a building comprising one embodiment of asystem for controlling an HVAC system in accordance with the principlesof the present invention;

FIG. 2 is block diagram of one embodiment of an HVAC communicationsystem; and

FIG. 3 is a schematic diagram of another embodiment of an interactiveHVAC system in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

The present invention relates to a climate control system having atleast a heating system controller for a heating system, or at least acontroller for compressor of an air conditioning or heat pump system,which controllers are capable of communicating to interactively controland improve the operation of the heating or air conditioning systems.One example of a climate control system 100 comprises a plurality ofcontrollers for controlling the operation of the climate control systemin accordance with the principles of the present invention is shown inFIG. 1. As shown and described, the climate control system 100 mayinclude at least one air conditioner 102 comprising an outdoor condenserfan 104, a compressor 106, and an associated controller 108, at leastone indoor circulator blower unit 150 having an indoor blower controller152 and at least one thermostat 120 for controlling the operation of thevarious units. Some embodiments of a climate control system may comprisea heating unit 140, such as an electric or gas-fired furnace, and arelated furnace controller 142, and a thermostat 120 for controlling theoperation of the furnace. The heating system may comprises a blower unit150 having a blower motor 154, which may be operated in a fan modeseparate from heating or cooling operation. In addition to an airhandler/blower controller 152, the circulating air system may furthercomprise a variable speed motor controller 156 for the circulatingblower motor 154. The thermostat 120 is capable of sensing thetemperature within the space and responsively initiating operation of anair conditioning or furnace unit when the sensed temperature is morethan a predetermined amount above or below a set point temperature ofthe thermostat 120. In response to a thermostat signal request forcooling, the outdoor compressor unit controller 108 will control theswitching of power to both a condenser fan motor 104 and a compressormotor 106, and the indoor blower controller 152 may directly control theblower motor 154 or indirectly control the variable speed motorcontroller to provide for air conditioning operation. Likewise, when thethermostat 120 signals a request for heating, the furnace controller 142controls the activation of the furnace 140 and the circulator blowermotor 154 or the circulator blower motor controller 152 to provide forheating operation. The outdoor compressor unit controller 108 may beconfigured to control a multi-stage or variable capacity compressormotor 106 as well as a variable speed condenser fan motor 104. Likewise,the indoor blower controller 152 and the furnace controller 142 may beconfigured to establish multiple operating speeds of the blower motor154. The circulator blower controller 152 may also comprise a variablespeed motor controller with an inverter driver for enabling variablespeed control of the blower motor.

The various controllers that control individual components within theclimate control system can further communicate bi-directionally withother individual controllers, to interactively control and improve theoperation of the HVAC system. Referring to FIG. 2, each of the variouscontrollers are connected to a low voltage source, such as a 24 volt ACtransformer 166, via hot and neutral power transmission lines 162 and164. One or more of the controllers are capable of transmitting a signalacross the hot and neutral power transmission lines connected to the 24volt transformer, such that at least one controller other than thetransmitting controller is capable of receiving the signal from thetransmission lines of the low voltage power source. For example, thethermostat 120 in connection with the 24 volt transformer power supplyis capable of transmitting a signal across the hot and neutral powertransmission lines connected to the 24 volt transformer, such that thefurnace controller 134 is capable of receiving the signal from thetransmission lines and controlling the operation of the furnace based onthe signal received from the thermostat.

Accordingly, the first embodiment of a system having one or morecontrollers comprises a heating system that includes a low-voltagelow-frequency alternating current power source in connection with acommon transmission line and a hot transmission line. The systemincludes a thermostat controller that is in connection with the commonand hot transmission lines of the low voltage power source, and iscapable of receiving and transmitting signals via the transmission linesof the low voltage power source. The heating system includes a heatingsystem controller that is also in connection with the common and hottransmission lines of the low voltage power source. The heating systemcontroller is capable of receiving signals from and transmitting signalsvia the transmission lines of the low voltage power source, wherein theheating system controller is configured to control the operation of theheating system in response to receiving one or more signals transmittedacross the low voltage transmission lines from the thermostat controllerwhich request operation of the heating system. The thermostat andheating system controller are connected to each other only through eachcontroller's individual connection to the hot and common power lines.

In a second embodiment of a system comprising at least a heating systemand one or more controllers, the controllers are capable ofsuperimposing signals onto the low-frequency low-voltage waveform beingconducted across the power transmission lines, to enable communicationwith other controllers. Referring to FIG. 2, the thermostat controller120 for example, comprises a microprocessor that is capable oftransmitting one or more signals for controlling the operation of aheating system. In the second embodiment, the microprocessor of thethermostat controller 30 comprises at least a transmit pin and a receivepin associated with a Universal Asynchronous Receiver Transmitter (UART)interface, for providing serial communication capability.

Likewise, the heating system or furnace controller 142 comprises amicroprocessor having a UART interface. The microprocessor of thefurnace or heating system controller 142 preferably controls theoperation of the furnace, and is a 28 pin PIC16F microprocessormanufactured by Microchip. However, the furnace controller mayalternatively comprise any microprocessor suitable for the controllerapplication. The UART interface of the microprocessor is capable ofsupporting automatic baud rate detection. The microprocessor is furthercapable of monitoring the UART RXD pin and detecting the start of areceived character by sampling an RXD signal until it detects a validstart bit comprising a low level for more than 7 cycles of the samplingclock, which is 7/16 of the baud rate. When a valid start bit isdetected, the receiver samples the RXD signal and detects subsequentdata bits and stop bits. The UART TXD pin is likewise capable oftransmitting a serial communication signal comprising a start bit, databits and a stop bit. The microprocessor's UART TXD and RXD interfacecommunicates signals to a Power Line Communication (PLC) transceiverthat is capable of superimposing the UART serial data signals over a 60hertz alternating current power line waveform.

Power Line Communication is a method of communicating that uses existingelectrical distribution lines, such as the wires connecting 24 volt ACpower to the various heating and cooling system components. Typicallythese devices operate by injecting a carrier wave of between 20 and 200kHz into the household wiring at the transmitter. The high frequencycarrier wave carries serial data superimposed over the low frequency 60hertz waves on electrical transmission lines. In the second embodiment,the carrier wave may be modulated by digital signals received via anUART interface, and superimposed on a 60 hertz waveform from a 24 voltAC power source. Each of the various controllers may be connected to the24 volt AC power source. Since the carrier signal may be propagatedthrough out the 24 volt electrical transmission line to othercontrollers in connection with the 24 volt AC power source,communication of data is provided for using the low voltage power lines.

One or more of the controllers include a PLC receiver that has anindividual address, such that the controller can be individuallycommanded by the signals that are transmitted over the 24 volt AC wiringand decoded at the PLC receiver. In the second embodiment, the furnacecontroller is one such controller that is capable of receiving a signalsuperimposed onto the 60 hertz waveform being conducted across the 24volt AC power transmission lines, which signal may include a commandspecific only to the heating system controller requesting operation ofthe heating system. The signal decoded by the controller's PLC receiveris then communicated to the UART RXD interface to the microprocessor ofthe controller. Likewise, one or more of the controllers include a PLCtransmitter or transceiver that is capable of superimposing a signalonto the 60 hertz waveform being conducted across the 24 volt AC powertransmission lines, to transmit one or more command signals toindividually command at least one other controller or HVAC component. Inthe second embodiment, the thermostat controller 120 is capable ofsuperimposing high frequency signals onto the low frequency low-voltagewaveform to transmit one or more command signals to the heating systemor furnace controller.

Accordingly, the second embodiment of a system having one or morecontrollers comprises at least a heating system that includes alow-voltage low-frequency alternating current power source that conductsa low-frequency low-voltage waveform being conducted across a hot andcommon power transmission line. The second embodiment further includes athermostat controller in connection with the common and hot transmissionlines of the low voltage power source, the thermostat controller beingcapable of superimposing high frequency signals onto the low frequencylow-voltage waveform. The thermostat controller is configured totransmit one or more signals across the hot and common powertransmission lines via the low frequency low-voltage waveform, forrequesting operation of the heating system. While the conventional HVACsystem typically involves a 24 volt AC signal sent from a conventionalthermostat to the furnace via a dedicated wire connected between thethermostat and the furnace, the thermostat controller of the secondembodiment is capable of transmitting a signal to the furnace controllervia the hot power transmission line “R” and the common powertransmission line “C”, independent of any signal being sent from thethermostat via a specific individual wire connected to the heatingsystem. Thus, in the second embodiment, the thermostat controller isconnected to a heating system or heating system controller only by thehot and common power transmission lines.

A third embodiment of a system having one or more controllers isprovided that comprises at least a cooling system that includes alow-voltage low-frequency alternating current power source that conductsa low-frequency low-voltage waveform across the hot and common powertransmission line. The third embodiment further includes a thermostatcontroller in connection with the common and hot transmission lines ofthe low voltage power source, the thermostat controller being capable ofsuperimposing high frequency signals onto the low frequency low-voltagewaveform. The thermostat controller is configured to transmit one ormore high frequency signals superimposed onto the low frequencylow-voltage waveform being conducted across the hot and common powertransmission lines, for requesting operation of a compressor of thecooling system. The conventional HVAC system typically involves a 24volt AC signal sent from a conventional thermostat to the compressorcontactor via a dedicated wire connected between the thermostat and thecompressor contactor, and a 24 volt AC signal sent from a conventionalthermostat to an air handler circulator blower via a dedicated wireconnected between the thermostat and the air handler unit. Thethermostat controller in the third embodiment is capable of transmittinga signal to an outdoor compressor unit controller via the hot powertransmission line “R” and the common power transmission line “C”,independent of any signal being sent from the thermostat controller viaa specific individual wire connected to the compressor controller. Thus,in the third embodiment, the thermostat controller is connected to acompressor controller of an air conditioning or heat pump system only bythe hot and common power transmission lines.

The third embodiment of a system includes an outdoor compressor unitcontroller in connection with the common and hot transmission lines ofthe low voltage power source. The compressor unit controller is capableof receiving the high frequency signals superimposed onto the lowfrequency low-voltage waveform that are transmitted by other controllersto the compressor controller. The compressor unit controller isconfigured to operate at least the compressor of the cooling system inresponse to receiving the one or more signals transmitted from thethermostat controller requesting operation of the compressor in adesired manner.

In some embodiments, a signal may be superimposed onto a low-frequencylow voltage waveform being conducted on the power transmission lines bymeans of a power line interface circuit that is capable of receivingserial data output from a microprocessor of the controller andtransmitting the digital data using carrier frequencies that aremodulated onto the 60 hertz 24 volt AC waveform being conducted on thehot and neutral power transmission lines. A digital data signaltransmitted via a carrier frequency that is modulated onto the 60 hertzpower line waveform may be extracted from the power line interfacecircuit and input to the microprocessor. The power line interfacecircuit comprises a connection means for connecting to the hot andcommon power transmission lines, a filter, and a power line interface ICchip. One example of a power line interface circuit provided byFreescale Semiconductor includes a power line interface IC chipHPCL-800J manufactured by Agilent Technologies, which is capable ofreceiving data through a UART interface in communication with themicroprocessor of the controller. In another example of an alternativeconstruction of a power line interface circuit, the circuit comprisesconnection means for coupling to the power transmission lines, a filterin connection with the connection means, and a IT800D power lineinterface IC chip manufactured by Yitran Communications, which iscapable of receiving data through a UART interface in communication withthe microprocessor. The microprocessor of a controller is accordinglyable to transmit a unique digital signal having identifying informationthat is specific to an individual controller within the heating,ventilation, and air conditioning system, such that a controller mayrequest a specific individual controller to operate its respectiveheating or cooling system components in a specific manner.

Referring to FIG. 3, a schematic shows a fourth embodiment of a climatecontrol system comprising various controllers for a heating system,ventilating fan, and an air conditioning and/or heat pump system (seeFIG. 1 for illustration of such systems). The climate control system 400comprises a thermostat controller 420, an integrated furnace controller442 for controlling a gas valve 444 and an igniter 446 of a heatingsystem 440, an indoor air handler controller 452 and a variable speedcirculator blower motor 454 associated with the heating system and/orair conditioning system that is indirectly controlled by controller 452,and an outdoor compressor/condenser fan unit controller 408 of an airconditioning system. The thermostat controller 420 is connected to hotand common 24 volt AC power transmission lines 462 and 466 in connectionwith a transformer 466. The thermostat controller 420 includes a powersupply circuit for providing a low voltage supply (such as 5 volts) to amicroprocessor 422 that controls the thermostat's operation. Thethermostat controller 420 further comprises a PLC interface integratedcircuit IC chip 424 that is in communication with the 24 volt AC powertransmission lines 462 and 466, as well as a UART interface 426 of themicroprocessor 422. The microprocessor 422 is capable of transmitting adigital data signal via the UART interface 426 to the PLC interface chip424, which is configured to superimpose the signal as a carrier waveonto the low voltage waveform that is being conducted via the powertransmission lines 462 and 466. The thermostat controller 420 mayaccordingly transmit a signal that is specific to an individualcontroller within the system, such as the integrated furnace controller442 for example, to request the furnace controller to operate itsrespective components in a desired manner.

In the fourth embodiment, the integrated furnace controller 442 isconnected to hot and common 24 volt AC power transmission lines 462 and464, and includes a power supply circuit for providing a low voltagesupply (such as 5 volts) to a microprocessor 448 that controls theintegrated furnace controller's 442 operation. The microprocessor 448 ofthe furnace controller 442 may be capable of controlling one or moreswitching means 474 for switching 120 volts AC line voltage for poweringan igniter 446 to a level sufficient to ignite gas. The microprocessor448 may further be capable of switching one or more relays 476 and 478for switching a gas valve 444 between low and high stage heating modes,where a multi-stage heating system is employed. The integrated furnacecontroller 442 further comprises a PLC interface integrated circuit ICchip 449 that is in communication with the 24 volt AC power transmissionlines, as well as a UART interface of the microprocessor 448. The PLCinterface chip 449 is capable of receiving and extracting a superimposedsignal transmitted by another controller via the power transmissionlines 462 and 464, and communicating the extracted signal to the UARTinterface of the microprocessor 448. The microprocessor 448 accordinglymay receive a signal that is addressed specifically to the integratedfurnace controller 442 requesting operation of the heating system by thethermostat controller 420. The microprocessor 448 is further capable oftransmitting a digital data signal via the UART interface to the PLCinterface chip 449, which is configured to superimpose the signal as acarrier wave onto the low voltage waveform that is being conducted viathe power transmission lines 462 and 464. The integrated furnacecontroller 442 may accordingly transmit a signal that has an intendeddestination or is addressed to a specific individual controller withinthe system, such as the variable speed circulator blower motorcontroller 452 for example, to request the variable speed circulatorblower motor 454 to operate the blower at a desired speed.

In the fourth embodiment, the indoor air handler or circulating airblower controller 452 has one or more variable speed circulator blowermotor relays 456 is connected to the hot and common 24 volt AC powertransmission lines 462 and 464, and includes a power supply circuit forproviding a low voltage supply (such as 5 volts) to a microprocessor 458that controls the variable speed circulating air blower controller'soperation. It should be noted that the air handler may further comprisea variable speed motor controller with an inverter driver for a variablespeed circulator blower motor 454, rather than a multi-speed blower withone or more speed selection relays 456. In some embodiments, themicroprocessor 458 may further be capable of monitoring a pair ofsensors 482 and 484 for determining the temperature difference acrossthe indoor air conditioner evaporator coil. The variable speedcirculating air blower controller 452 further comprises a PLC interfaceintegrated circuit IC chip 460 that is in communication with the 24 voltAC power transmission lines 462 and 464, as well as a UART interface ofthe microprocessor 458. The PLC interface chip 460 is capable ofreceiving and extracting a superimposed signal transmitted by anothercontroller via the power transmission lines 462 and 464, andcommunicating the extracted signal to the UART interface of themicroprocessor 458. The microprocessor 458 accordingly may receive asignal that is addressed specifically to the variable speed circulatingair blower controller 452 requesting operation of the variable speedcirculator blower motor 454 and the one or more speed selection relays456. The microprocessor 458 is further capable of transmitting a digitaldata signal via the UART interface to the PLC interface chip 460, whichis configured to superimpose the signal as a carrier wave onto the lowvoltage waveform that is being conducted via the power transmissionlines 462 and 464. The variable speed circulating air blower controller452 may accordingly transmit a signal that that has an intendeddestination or is addressed to a specific individual controller withinthe system, such as a thermostat controller 420 for example, to notifythe thermostat controller of blower motor operating information, such asa reduced capacity or a disabled condition, for example.

In the fourth embodiment, the outdoor compressor/condenser fan unitcontroller 408 is connected to hot and common 24 volt AC powertransmission lines 462 and 464, and includes a power supply circuit forproviding a low voltage supply (such as 5 volts) to a microprocessor 412that controls the compressor/condenser fan unit's operation. The outdoorcompressor and condenser fan unit controller 408 further comprises a PLCinterface integrated circuit IC chip 414 that is in communication withthe 24 volt AC power transmission lines 462 and 464, as well as a UARTinterface 416 of the microprocessor 412. The PLC interface chip 414 iscapable of receiving and extracting a superimposed signal transmitted byanother controller via the power transmission lines 462 and 464, andcommunicating the extracted signal to the UART interface 416 of themicroprocessor 412. The microprocessor 412 accordingly may receive asignal that is addressed specifically to the compressor/condenser fanunit controller requesting operation of the compressor and condenser fan(such as a request from the thermostat controller 420). Themicroprocessor 412 is further capable of transmitting a digital datasignal via the UART interface 416 to the PLC interface chip 414, whichis configured to superimpose the signal as a carrier wave onto the lowvoltage waveform that is being conducted via the power transmissionlines 462 and 464. The compressor/condenser fan unit controller 408 mayaccordingly transmit a signal that that has an intended destination oris addressed to a specific individual controller within the HVAC system,such as the thermostat 420 for example, to notify the thermostat of anoperating condition of the compressor. The compressor controller 408 maybe further capable of controlling a second stage solenoid 418 associatedwith a high capacity and low capacity multi-stage compressor 406.Likewise, the compressor controller 408 may be further capable ofcontrolling a heat pump reversing valve 410 to enable operation of thecompressor 406 in a heat pump mode.

The present means for communicating signals within an HVAC system is asignificant departure from conventional thermostats that include severalwires connected to various HVAC system controls and components. Forexample, in a conventional system, heating is activated when theconventional thermostat switches a 24 volt AC power source to supply a24 volt AC signal to a specific individual wire that is connected to aheating system. Likewise, fan operation is activated when theconventional thermostat switches a 24 volt AC power source to supply a24 volt AC signal to another specific individual wire that is connectedto a blower fan motor or a fan contactor. The conventional thermostatswitches a 24 volt AC signal to a specific wire for actuating eachindividual heating, fan or cooling system component. Accordingly, eachwire in connection with a conventional thermostat is connected to adifferent HVAC system component. In heating system or thermostatreplacement situations, wiring installed through the walls to anexisting thermostat may not be color coded or distinguished from eachother, and can potentially be inadvertently confused or interchangedwith each other. This can make installation of a replacementconventional thermostat difficult, and can lead to inadvertentmiss-wiring of the thermostat to the wrong HVAC component.

The fourth embodiment of a system provides for sending digital signalsan intended destination or address of a specific controller in thesystem, where the signals are transmitted across the shared low voltagepower transmission lines supplying power to each controller or systemcomponent. The digital data signal superimposed on the 24 volt ACwaveform, and may be received by each controller or component connectedto the 24 volt ac power transmission lines. The present system does notrequire a specific direct wire connection from the thermostat to eachHVAC component, for transmission of a signal to a specific individualwire associated with a specific individual HVAC component, but ratheruses only the hot and common power transmission lines for sendingsignals to eliminate the need for a dedicated individual wire connectingeach specific individual controller to the thermostat. Thus, the variouscontrollers are connected to each other only through the hot and commonpower transmission lines. In the fourth embodiment, the thermostatcontroller 420 may transmit a signal via the low voltage powertransmission lines that includes information identifying the intendeddestination or address of a specific controller. Where the signal isrequesting operation of a specific individual controller, the signalincludes a unique command that is specific to only the individualcontroller that the thermostat is requesting operation of. Thus, thethermostat controller 420 could send a signal that only requestsoperation for a specific controller, unlike the conventional thermostatthat sends a 24 volt AC signal (or half wave rectified 24 volt signal)across an individual wire that could activate any HVAC component whichis connected to the wire.

The various embodiments of an HVAC system provide a means oftransmitting digital data signals to components and controllers, whichsignals are not capable of “activating” an HVAC component as a 24 voltsignal (or half wave rectified 24 volt signal). The transmitted digitalsignals are sent across the low-voltage power transmission lines thatsupply power to the various HVAC controllers and components, rather thatvia a specific individual wire used to control activation of an HVACsystem component. Unlike conventional systems, where a 24 volt ACwaveform or a rectified 24 volt AC waveform may be conducted via aspecific individual wire to activate an HVAC control connected to theindividual wire, or where a 24 volt AC waveform that powers a controlmay be half wave rectified to both signal activation of the control andpower the control as well, the present means of communication does nottransmit a signal via a specific wire connected to an individual HVACcontrol to “activate” the HVAC control. Rather, the present meanstransmits a digital signal that will only request operation of aspecific HVAC component, by virtue of a command that is unique to thespecific controller. This prevents the possibility of tampering that ispresent in a conventional system, where an individual wire thattransmits a 24 volt AC “activation” signal (or half wave rectifiedsignal) could be jumpered or connected to an HVAC control or componentto operate the component.

Various embodiments of the present invention also provide forinteractive communication between a first controller and anothercontroller in the heating, ventilation, and cooling system, to improvecontrol of HVAC system operation. For example, in the fourth embodiment,the system comprises an integrate furnace controller 442, forcontrolling the operation of one or more components of the heatingsystem. The integrate furnace controller 442 is capable of modifying theoperation of the one or more heating system components it controls, suchas a two-stage gas valve, in response to receiving informationtransmitted via the power transmission lines about the operation ofanother controller or component within the heating, ventilation, and airconditioning system. The controller for a circulating air blower may,for example, include a variable speed circulator blower motor controllerwith an inverter driver, which if overheated would reduce the speed ofthe circulator blower. The blower controller could responsivelycommunicate its reduced speed information by transmitting a signal viathe hot and common power transmission lines. The signal may be intendedfor a specific controller, such as the thermostat controller 420 or theintegrated furnace controller 442. Where the signal is intended for theintegrated furnace controller 442, the integrated furnace controller 442would respond to the blower's reduced speed signal by modifying itsoperation to that of only low stage heating operation to correspond tothe reduced circulator blower speed. The integrated furnace controller442 would operate in low stage heating mode even though the thermostatcontroller 420 has requested the integrated furnace controller 442 tooperate the furnace at high stage heating. Where the signal includes anaddress or intended destination of a thermostat controller 420, theintegrated furnace controller 442 may still “listen” to the signalintended for the thermostat controller 420, and responsively restrictoperation to low stage heating. Likewise, where the furnace shuts offafter sensing an over-temperature condition, the furnace controller maysignal the blower controller to continue operating until theover-temperature condition is alleviated. Accordingly, a single signaltransmission intended for a specific controller that includesinformation of an operating condition can improve operation of multiplecontrollers. The integrated furnace controller 442 could, for example,communicate the restriction of its heating operation to the thermostatcontroller 420, which would alert the occupant of a need for service.

In one aspect of the present invention, some embodiments provide one ormore controllers for a climate control system, where at least onecontroller is capable of modifying the operation of one or more systemcomponents under its control in response to receiving a signaltransmitted by another controller that includes information about theoperation of another component or controller in the climate control. Forexample, in the fourth embodiment, the system may comprise at least twocontrollers for controlling the operation of one or more components ofthe cooling system. The at least two controllers can communicate via thepower transmission lines to provide for operation in either a fullcapacity mode of operation or a reduced capacity mode of operation,based on the communication by one of the at least two controllers ofinformation relating to the operation or condition of a component underthe individual controller's control. For example, after the thermostatcontroller 420 transmits a signal requesting compressor operation, afirst air handler/circulating air blower controller 452 is not capableof operating, a first air handler controller may detect the operationfailure (by a pressure sensor, motor current sensor, or temperaturesensor for example) and transmit a signal via the power transmissionlines communicating the failure to another controller. The signal may beintended for a specific controller, such as the thermostat controller420 or the compressor unit controller 408. Where the signal is intendedfor the compressor unit controller 408, the compressor unit controller408 could respond to the information of a blower failure by modifyingits operation to shut down the compressor to protect the compressormotor from possible damage due to the indoor coil unit freezing up. Thecompressor unit controller 408 would shut down even though thethermostat controller 420 is still requesting operation of thecompressor. Where the signal includes an address or intended destinationof a thermostat controller 420, the compressor unit controller 408 maystill “listen” to the signal intended for the thermostat controller 420,and responsively shut down the compressor to protect the compressor. Thecompressor unit controller 408 could subsequently transmit a signal viathe power transmission lines that is addressed to the thermostatcontroller 420, for communicating the shut down of the compressor due tothe information on the failed circulator blower, such that thethermostat controller 420 may alert the occupant of a need for service.

In yet another aspect, some embodiments of an interactive system maycomprise at least two controllers that communicate information via thepower transmission lines to provide for controlling operation of one ormore system components in either a full capacity mode or a reducedcapacity mode of operation based on the communication of informationrelating to the operation of one of the at least two controllers. Forexample, in the fourth embodiment, the system comprises at least twocontrollers that together provide for the operation of a multi-stage airconditioning system capable of operating in a high capacity or a lowcapacity mode. If a first compressor unit controller is not able tocontinuously operate the compressor in high capacity mode (due to a highdischarge line temperature, or high motor current for example), thecompressor unit controller could restrict operation to low capacity modeand transmit a signal via the power transmission lines communicating therestriction. The signal may be intended for the second controller 452for an air handler circulating air blower, or for the thermostatcontroller 420. Where the signal is intended for the circulating airblower controller 452, the circulating air blower controller 452 couldreceive the signal and responsively reduce the circulator blower speedto correspond to the low capacity compressor mode of operation to allowthe air conditioning system to operate in a limp-along mode until theair conditioning system can be serviced. The compressor and circulatingair blower would be operated at a low capacity mode even though thethermostat controller 420 is still requesting operation at highcapacity. Where the signal includes an address or intended destinationof a thermostat controller 420, the circulating air blower controller452 may still “listen” to the signal intended for the thermostatcontroller 420, and responsively reduce the circulator blower speed tocorrespond to the low capacity compressor operation mode.

In yet another aspect, some embodiments of an interactive system maycomprise controllers having a microprocessor that is capable oftransmitting one or more unique data signals through a UART interface.The microprocessor is configured to communicate a valid start bitfollowed by subsequent data bits of a signal to be transmitted via thepower lines. Referring to Table 1 below, the serial data signal includesone or more data bits, the first data bit of which comprises adestination node or address that the serial data signal is intended tobe received at. The serial data signal further comprises a subsequentdata bit that includes the sender's node or address, and may furtherinclude a subnet node or address. The data signal may further comprise anode type data bit and device request data bit, which permit acontroller (such as a thermostat) to take control of the communicationtransmissions being sent over the power transmission lines.

TABLE 1 Message Configuration Addressing 3^(rd) Party Special FunctionMessages CRC Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7Bytes 8- Bytes N (N-2) Destination Sender Subnet Node Device PayloadMessage Packet Payload Data Checksum Node Address Type Request ConfigType Number Length Payload Address 8 Bits 8 Bits 8 Bits 8 Bits 4 Bits 4Bits 8 Bits 1 Byte 1 Byte 1 to 245 2 Bytes bytes (0-255) (1-255) (0-255)(0-255) (0-15) (0-15) (0-255) (0-255) (0-245) (1-N) (0-65535)

The serial data signal transmitted by the controllers comprises a nodetype data bit, which permits controllers that are capable of a listenmode to monitor signals transmitted by other controllers, such that oneor more listening controllers may modify the operation of theirrespective HVAC components in response to operating information signalstransmitted by other controllers. For example, if an outdoor compressorunit controller communicates a signal indicating that the compressor hasbeen restricted to low capacity operation, the indoor air handler unitcontroller listening to the signal could respond to the operatinginformation by modifying operating of the circulator blower to a reducedspeed that corresponds with the low capacity compressor operation. Nodetypes could include controllers for any of the following number of HVACcomponents or subsystems listed in Table 2 below.

TABLE 2 Node Types Node Node Type ID Thermostat 0 Gas Furnace 1 AirHandler 2 Unitary Air Conditioner 3 Unitary Heat Pump 4 Electric Furnace5 Package System (Gas) 6 Packager System (Electric) 7 Ceiling fan 8Whole house fan 9 Air Exchanger 10 Dehumidifier 11 Electronic AirCleaner 12 ERV 13 Humidifier (Evap) 14 Humidifier (Steam) 15 HRV 16 IAQAnalyzer 17 Media Air Cleaner 18 Zone control 19 Zone master 20 UV Light21 Boiler 22 Gas Water Heater 23 Electric Water Heater 24 CommercialWater Heater 25 Pool Heater 26 Bus Interface Module 27 Gateway 28Diagnostic Device 29 Lighting Control 30 Security System 31 Fuel cell 32Spare 33-255

In the various embodiments, the controllers monitor the 24 volt waveformconducted via the power transmission lines for transmission signals, andare capable of listening to data signals from various transmissionsources that are intended for a different destination address (orcontroller). While a signal may be intended for a given destinationaddress, other controllers may still “listen” to or receive thesesignals and analyze them depending on the node type of the sender of thesignal. The listening mode of the controllers provides for sharinginformation that reduces the number of signal transmissions byeliminating request signals for information, and also provides forimproved diagnostic capability, component safety, fault protection, andoccupant safety.

For example, a transmitted signal may includes a source address (andnode type) of an outdoor compressor unit controller and a destinationaddress of the thermostat, and may communicate diagnostic information ofa high Discharge Line Temperature (DLT) upon start up of the compressor,indicating a possible low refrigerant charge that may require servicing.A controller for the indoor air handler may listen to the message fromthe compressor unit node type, and responsively compare the sensedtemperature difference across the indoor A-coil to a predetermined deltato evaluate whether the difference is out of range, which would confirmthat the refrigerant charge is low. The indoor air handler controllercould then communicate a confirmation of a low refrigerant charge to thethermostat controller, to prompt the thermostat to alert the occupant ofthe need for servicing of the low charge condition.

In another example, a thermostat controller could transmit a signal to acontroller 408 for a compressor of an air conditioning or heat pumpsystem to request operation of the compressor. The controller of the airhandler's circulating air blower could “listen” to or receive the signaland responsively check its line voltage level sensing circuitryassociated with a variable speed inverter driver for a blower motor, toverify that the line voltage level is not below a threshold valueindicative of a brown out condition. If the circulating air blowercontroller 452 determines that a low line voltage condition exists, thecirculating air blower controller 452 could transmit a signal includingthe low line voltage information to the compressor controller 408, whichcould responsively discontinue operation to protect the compressor frombeing damaged by the low voltage condition. This type of interactivecommunication can accordingly provide component protection againstdamage for one of more components in the climate control system.

In another example, occupant safety is provided in a situation of apresence of an unsafe level of carbon monoxide. In a climate controlsystem that at least includes a fuel-fired heating system and athermostat controller in connection with a common and hot powertransmission lines, the system may further include a fuel-fired waterheater in connection with the power transmission lines. A controller forthe fuel fired water heater is connected to the hot and common powertransmission lines and is capable of receiving and transmitting signalssuperimposed onto the low frequency low-voltage waveform. The fuel-firedheating system controller 442 is capable of modifying the operating ofthe heating system by shutting down, in response to “listening” to asignal transmitted by the water heater controller that is intended forthe thermostat controller 420, which includes information about thepresence of a harmful level of carbon gas or a presence of flammablevapors. In either case, the furnace or heating system would discontinueoperation to help improve the safety of the occupants. Likewise, acarbon monoxide detector 492 could also be configured to provide anindication of a harmful carbon monoxide level which may be communicatedthrough a high frequency signal superimposed onto the low frequencylow-voltage waveform to alert the thermostat controller. The heatingsystem controller would be capable of “listening” to or receiving thesignal intended for the thermostat controller which includes informationabout a harmful carbon monoxide level, and responsively discontinuesoperation of the heating system (eg.—gas valve 444 and combustion blower404).

The usage of node types is one way of receiving data from other devicesone the network without having to initiate a request signal forinformation. The various controllers or subsystem devices can be in alisten mode to monitor the signals transmitted by certain node types toget information from that subsystem device or controller. Alternatively,the various controllers can also request transmission of informationfrom other controllers. In order to determine what can be requested fromother controllers or devices that are in communication via the powertransmission lines, a controller device may transmit a device request toquery what types of devices are present.

The serial data signal transmitted by the controllers comprises a devicerequest bit, which enables an controller to request another controllerthat is controlling communication to release control, such that therequesting controller may be allowed to communicate a request forspecific information (from another controller for example) in apeer-to-peer manner. For example, if an outdoor compressor unitcontroller detects a possible low refrigerant charge condition, theoutdoor compressor unit controller could request the indoor air handlerunit controller to communicate specific information relating to whetherthe sensed temperature difference across the A-coil is out of range,which would confirm that the air conditioner refrigerant charge is low.This information could also be communicated to the thermostat to alertan occupant of the low refrigerant charge condition.

In some embodiments, a communication coordinator may be employed inconnection with the power transmission lines. Where a communicationcoordinator is used, a controller device may transmit via the powertransmission lines a request of the coordinator to provide a networkconfiguration request. The request is made after the coordinator makes aperiodic request of subordinate device status. This would allow anindividual controller to include itself in the network of othercontrollers identified by the coordinator. Each controller device (ornode) may further communicate a request to the communication coordinator(after the coordinator makes a periodic request of subordinate devicestatus) to take control of the communication being sent across the powerlines, for enabling the requesting controller to transmit a signalintended for another controller. The coordinator would respond bysending signals to controllers other than the requesting controller tosuspend transmission until the next periodic request for status by thecoordinator. The requesting controller could then transmit a signalintended for another controller that contains a request for operation,or relevant operating information, for example. In this manner, eachcontroller may communicate to other controllers via the power lineswithout a likelihood of signal interference, since the transmittingcontrol would have dominant control over the lines.

The serial data signal transmitted by the controllers comprises apayload data configuration byte. The payload configuration bits are usedin determining what type of data packet is being received. These bitsare located in byte 3 of every data packet sent in bits 0-3. The messagetype is contained in Byte 5 of the packet, and may provide informationas to whether the signal is interrogating or requesting information fromanother controller or a component, whether the signal is of a sensordata type, whether the signal is a unique command signal intended for aspecific controller or component in the system, or whether the signal isan operating informational message intended for a specific controller inthe system, such as a thermostat. The message may be a code which othercontrollers may recognize. The message may also be a text messageintended to be displayed by the thermostat controller to an occupant. Inthis manner, a controller may provide more specific repair ormaintenance information than a code. Table 2 below outlines some of thetypes of messages that may be employed in the various embodiments of anHVAC system.

TABLE 2 Message Type. Message Type Message Name Description 0 Ready Usedto make normally subordinates a coordinator 1 Status Request Used torequest operating status of a 2 Status Reply controller or itsrespective components 3 Control Command Commands a specific controller/component to operate in a desired mode 4 Configuration InstallationParameter Info used to Request configure controllers and components 5Configuration Data 6 Sensor Read Serial communication by any external/Request internal sensors in a subsystem that 7 Sensor Data can be sharedwith the system 8 Spare 9 Set Address 10 Event Request Request Datadefined as historical 11 Event Reply operating information of a specificcontroller or component in the system. 12 ID Request Identification Dataof individual 13 ID Set controllers and components in the 14 ID Replysystem 15 Node Type Request 16 Node Type Reply 17 Message Config Used todetermine which messages are Request applicable per specific componentor 18 Message Config controller in the system. Reply 19 Display ControlUsed to take control of the thermostat Request display to provideinstallation/ 20 Display Control diagnostic/System Checks or any Replyother subsystems needs. (text message may vary in length) 21 SharedDevice Installation Specific Configuration Data Request Data used fortransmitting data to shared networks or external network

The various embodiments provide for one or more controllers inconnection with low voltage power lines for powering the one or morecontrollers, which controllers are further capable of transmitting oneor more communication signals via the low voltage waveform. While eachsignal may be intended for a specific controller, at least onecontroller may listen to signals intended for other controllers and maymodify the operation of at least one component that the at least onecontroller has control over in response to receiving a signal that isintended for another controller which includes information about theoperation of a component within the system. The one or more controllersmay transmit text messages to a thermostat controller to alert anoccupant of specific maintenance requirements, such as a low refrigerantcharge or an over-temperature condition of the furnace. The controllersin the various embodiments could continue to provide cooling or heatingoperation in a “limp along” mode, while alerting the occupant ofspecific service or repair needs via a text message, before the heatingor cooling system becomes inoperable. The description of the inventionis merely exemplary in nature and, thus, variations that do not departfrom the gist of the invention are intended to be within the scope ofthe invention. Such variations are not to be regarded as a departurefrom the spirit and scope of the invention.

1. A climate control system comprising: an alternating current low voltage transformer that conducts a low-frequency low-voltage waveform across hot and common power transmission lines; a thermostat controller, a controller for a heating system, and at least a controller for a compressor of a heat pump or air conditioning system, the thermostat controller, heating system controller and compressor controller being connected to each other only through each controller's individual connection to the hot and common power transmission lines; wherein each of the individual thermostat, heating system and compressor controllers are configured to recognize a command that is unique to the specific thermostat, heating system controller or compressor controller, which unique command will only request operation of the specific controller, and each controller is capable of transmitting one or more signals that are superimposed onto the low-frequency low-voltage waveform and include information identifying a destination controller that the signals are intended for.
 2. The climate control system of claim 1 wherein the thermostat controller is capable of transmitting one or more signals which specifically request operation of only the heating system controller for establishing operation of the heating system only, and one or more signals which specifically request operation of only the compressor controller for establishing operation of the compressor only.
 3. The climate control system of claim 1, wherein at least one controller is capable of modifying the operation of at least one component that the at least one controller has control over in response to receiving a signal that is intended for another controller which includes information about the operation of at least one component within the climate control system.
 4. The climate control system of claim 1 wherein the one or more signals include information identifying the controller that is transmitting the signal and the intended destination controller.
 5. The climate control system of claim 1 further comprising a controller for a circulating air blower that is connected to the hot and common power transmission lines and is capable of transmitting high frequency signals superimposed onto the low frequency low-voltage waveform, wherein the compressor controller is capable of modifying the operation of the compressor in response to receiving a signal transmitted by the circulating air blower controller which is intended for the thermostat controller and includes information about circulating air blower operation being disabled or at a reduced capacity.
 6. The climate control system of claim 1 further comprising a controller for a circulating air blower that is connected to the hot and common power transmission lines and is capable of transmitting high frequency signals superimposed onto the low frequency low-voltage waveform, wherein the heating system controller is capable of modifying the operation of the heating system in response to receiving a signal transmitted by the circulating air blower controller which includes information about a blower motor operation being disabled or at a reduced capacity.
 7. The climate control system of claim 1 further comprising a controller for circulating air blower that is connected to the hot and common power transmission lines and is capable of receiving and transmitting high frequency signals superimposed onto the low frequency low-voltage waveform, the circulating air blower controller being capable of modifying the operating capacity of the circulating air blower in response to receiving a signal which includes information about a reduced operating capacity of either the compressor or the heating system.
 8. The climate control system of claim 1 wherein the thermostat controller is capable of transmitting one or more command signals that are unique to the heating system controller and the compressor controller respectively, for requesting respective operation of the heating system or compressor controller in a desired mode.
 9. The climate control system of claim 1 wherein the one or more signals include information relating to the operation of a system component controlled by the controller that is transmitting the signal.
 10. The climate control system of claim 1 further comprising a carbon monoxide sensor that provides an indication of a harmful carbon monoxide level which may be communicated through a high frequency signal superimposed onto the low frequency low-voltage waveform that is intended for the thermostat controller, wherein the heating system controller is capable receiving the signal intended for the thermostat controller which includes information about a harmful carbon monoxide level and responsively discontinuing operation of the heating system.
 11. The system of claim 1, wherein the one or more signals that are superimposed onto the low-frequency low-voltage waveform include information of the address of a controller that the signals are intended for, and wherein controllers other than the destination controller are configured to listen to the signal intended for another controller and analyze them depending on a node type of the sending controller.
 12. The system of claim 1, wherein the controllers are configured to establish operation in either a full capacity mode of operation or a reduced capacity mode of operation based on the communication of information by one of the controllers relating to the operation or condition of a component of the climate control system. 